Background
Green Onions
What type of study was conducted among those who dined at restaurant A in early October?
Case- control
How many patients were hospitilized?
124
True or False: Generating a hypothesis is unnecessary if the source of an outbreak is obvious
False! (Even if the source seems obvious, a hypothesis should still be generated and tested to confirm the findings)
True or False: Washing vegetables with chlorinated water can completely eliminate hepatitis A contamination
False! (It reduces but does not completely eliminate contamination)
Where did the major outbreak from the study occur?
Pennsylvania
Who were the cases?
Patients who were Pennsylvania residents, who ate at Restaurant A and obtained hep A
How many died?
3
During the investigation of the hepatitis A outbreak, what was hypothesized as the primary source of contamination?
Green onions grown in Mexico
What public health action did the FDA take after the hepatitis A outbreak linked to green onions?
They issued an import ban on green onions from implicated farms in Mexico.
When did the major outbreak from the study occur?
November 2003
Who were the controls?
meal companions of patients
What disease was identified from unusual juvenile arthritis cases?
Lyme disease
True or False: In the hepatitis A outbreak, the INITIAL hypothesis was that the outbreak was caused by contaminated water
False! (The initial focus was on food items, specifically green onions in mild salsa)
What is a key step mentioned for restaurant staff to prevent cross-contamination during food preparation?
Use proper washing methods for produce and ensure preparation areas are sanitized
True or False: Hepatitis A virus can remain infectious on environmental surfaces for at least one month
True!
What other procedures were measured (article 1)?
nucleic acid sequencing, statistical analysis, assessment of employees and the environment
True or False: Hot salsa was associated with illness
False, only the mild salsa
According to Reingold, what is often the first step in investigating an outbreak?
Establishing case definitions
Name just one strategy written in the article about how public health officials help prevent future hepatitis A outbreaks in restaurants?
By ensuring proper food handling practices, implementing hygiene training for staff, and encouraging vaccination for at-risk individuals
True or False: there are > 5% cases of Hepatitis A virus in the US annually
False!
What were the 4 major detection sources mentioned in the Outbreaks investigations article?
Clinicians, infection control nurses, lab workers.
Surveillance data (e.g., hepatitis B in dental patients).
Media reports (e.g., news alerts).
Public complaints (e.g., foodborne illnesses).
What was the median age mentioned of patients affected in the Pennsylvania hepatitis A outbreak?
34 years
What hypothesis testing method did the hepatitis A investigation use to confirm green onions as the contamination source?
Logistic regression models analyzing odds ratios for food items
During the hepatitis A outbreak investigation, what specific preparation practice for green onions was identified as a potential contributor to cross-contamination?
Rinsing green onions while they were still bundled, which may have facilitated the spread of contamination